| Method of preparing halogenoalkyldialkyl chlorosilane -> Monitor Keywords |
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  Method of preparing halogenoalkyldialkyl chlorosilaneRelated Patent Categories: Organic Compounds -- Part Of The Class 532-570 Series, Azo Compounds Containing Formaldehyde Reaction Product As The Coupling Component, Heavy Metal Containing (e.g., Ga, In Or T1, Etc.), Carbon Attached Directly Or Indirectly To The Silicon By Nonionic Bonding (e.g., Silanes, Etc.), Processes, Silicon To Carbon Bond Formed, By Substitution Of Silicon Bonded HydrogenThe Patent Description & Claims data below is from USPTO Patent Application 20070185344. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] The present invention relates to a process for the preparation of haloalkyldialkylhalosilane. [0002] More particularly, the present invention relates to a process for the preparation of 3-halopropyldimethylchlorosilane by hydrosilylation of dimethylhydrochlorosilane using allyl chloride and a catalyst based on a platinum ore metal, in particular iridium, and optional recovery of the said metal. The reaction involved in this example is as follows: [0003] In this type of reaction, the amounts of platinum ore metal involved are often high with the aim of obtaining a satisfactory yield. Under these conditions, in order for the process to remain economically advantageous, it is necessary to recover the platinum ore metal in order to be able to reuse it as catalyst. [0004] Another route for improving the economics of the process would be to optimize the activity of the catalyst. To do this, it is arranged for the degree of conversion (DC) of the hydrosilane (II) to be increased or, for a given DC, for the selectivity (S) of the catalyst to be significantly increased. [0005] In the present account, the degree of conversion (DC) and the selectivity (S) correspond to the following definitions: TT = number .times. .times. of .times. .times. moles .times. .times. of .times. .times. SiH .times. .times. units .times. .times. consumed number .times. .times. of .times. .times. moles .times. .times. of .times. .times. SiH .times. .times. units .times. .times. or .times. .times. of .times. .times. ( II ) .times. .times. introduced S = number .times. .times. of .times. .times. moles .times. .times. of .times. .times. ( I ) number .times. .times. of .times. .times. moles .times. .times. of .times. .times. SiH .times. .times. units .times. .times. or .times. .times. of .times. .times. ( II ) .times. .times. introduced [0006] The hydrosilylation of allyl chloride by dimethylhydrochlorosilane catalyzed by an iridium-based catalyst is disclosed in the following patent documents: JP-B-2938731 and JP-A-7126271. The catalysts disclosed in these patent documents are of the [Ir(diene)Cl].sub.2 type and make possible access to full degrees of conversion (DC=100%) of the dimethylhydrochlorosilane with a good selectivity of the reaction (good yield YD of 3-chloropropyidimethylchlorosilane). However, these performances are achieved at the cost of very large amounts of catalyst. [0007] EP-A-1 156 052 (=U.S. Pat. No. 6,359,161) and DE-A-10053037 (US-A-2002/0052520) disclose: [0008] in the presence of free COD for increasing the yield: [0009] EP-A-1 156 052: 4.times.10.sup.-3 mol of free COD per 1.times.10.sup.-4 mol of [Ir(COD)Cl].sub.2: i.e. a ratio of 40, [0010] versus DE-A-10053037: 9.2.times.10.sup.-4 mol of free COD per 4.5.times.10.sup.-6 mol of [Ir(COD)Cl].sub.2: i.e. a ratio of 204. [0011] BE-B-785343 (U.S. Pat. No. 3,798,252) discloses the hydrosilylation of allyl chloride by trichlorohydrosilane in the presence of chloroplatinic acid in solution in cyclohexanone (removal of water from the solution using Na.sub.2SO.sub.4). The ketone is combined with the platinum in order to improve the selectivity of the reaction. [0012] In this state of the art, one of the essential objects of the present invention is to provide a means which makes it possible to optimise the activity of the iridium-based catalyst in comparison with what is taught in the prior art [in particular EP-A-1 156 052 (=U.S. Pat. No. 6,359,161) and DE-A-10053037 [US-A-2002/0052520]. [0013] Another essential object of the invention is to provide a process for the preparation of a haloalkyldialkylhalosilane of the above type which is effective, economical and easy to implement. [0014] These objects, among others, are achieved by the invention, which relates, first, to a process for the preparation of a haloalkyldialkylhalosilane of formula (I): Hal-(R.sup.2R.sup.3)Si--(CH.sub.2).sub.s-Hal by hydrosilylation reaction of a reaction medium comprising: [0015] a silane of formula (II): Hal-(R.sup.2R.sup.3)Si--H [0016] and an alkenyl halide of formula (III): CH.dbd.CH--(CH.sub.2).sub.s-2Hal [0017] in the presence of a catalytically effective amount of a hydrosilylation catalyst based on iridium in the oxidation state I or III, in which formulae (I), (II), (III): [0018] the symbol Hal represents a halogen atom chosen from the chlorine, bromine and iodine atoms, [0019] the symbols R.sup.2 et R.sup.3, which are identical or different, each represent a monovalent hydrocarbon group chosen from a linear or branched alkyl radical having from 1 to 6 carbon atoms and a phenyl radical, and [0020] s represents are integ between 2 and 10 incclusive, the said process being characterized in that at least one auxiliary in the free or supported state selected from the group of compounds consisting of: [0021] (i) ketones, [0022] (ii) ethers, [0023] (iii) quinones, [0024] (iv) anhydrides, [0025] (v) unsaturated hydrocarbon compounds (UHC) having an aromatic nature and/or comprising at least one C.dbd.C double bond and/or at least one C.ident.C triple bond, it being possible for these unsaturated bonds to be conjugated or nonconjugated, the said UHCs being linear or cyclic (mono- or polycyclic), having from 4 to 30 carbon atoms, having from 1 to 8 ethylenic and/or acetylenic unsaturations and optionally comprising one or more heteroatoms, [0026] (vi) and their mixtures, is added to the reaction medium, with the condition according to which, when the auxiliary comprises one or more UHCs as defined above, then this (these) UHC(s) is (are) mixed with at least one other auxiliary other than a UHC. [0027] In accordance with the present invention, the term "mixtures (vi)" of auxiliary compounds is understood in particular to mean: [0028] (vi.1) any mixture of compounds (i) and/or (ii) and/or (iii) and/or (iv) and/or (v), [0029] (vi.2) any compound having a molecule comprising at least two different chemical functional groups selected from the group consisting of the ketone, ether, anhydride, quinone, C.dbd.C and C.ident.C functional groups characteristic of the compounds (i) to (v), [0030] (vi.3) any mixture of compounds (vi.2), [0031] (vi.4) and any mixture based on at least one compound (i) to (v) and on at least one compound (vi.2). [0032] According to a preferred form, use is made of a catalyst based on iridium in the oxidation state 1, in the structure of which each iridium atom corresponds to the complex form of the Ir(L).sub.3X type where the symbols L and X have the definitions given in the work "Chimie Organometallique" [Organometallic Chemistry] by Didier Astruc, published in 2000 by EDP Sciences (cf. in particular page 31 et seq.). [0033] According to a more preferred form, the catalyst corresponds to the formula (I): [Ir(R.sup.4).sub.x(R .sup.5)].sub.y (IV) [0034] in which: [0035] the symbol R.sup.4 represents either a monodentate ligand L, and in this case x=2, or a bidentate ligand (L).sub.2, and in this case x=1, and [0036] the symbol R.sup.5 represents either Hal as defined above, and in this case y=2, or a ligand of type LX, and in this case y=1. [0037] Catalysts corresponding to the more preferred definition mentioned above in which: [0038] R.sup.4 is a ligand comprising at least one C.dbd.C double bond and/or at least one C.ident.C triple bond, it being possible for these unsaturated bonds to be conjugated or nonconjugated, the said ligand being linear or cyclic (mono- or polycyclic), having from 4 to 30 carbon atoms, having from 1 to 8 ethylenic and/or acetylenic unsaturations and optionally comprising one or more heteroatoms, and [0039] R.sup.5, in addition to Hal, can also represent a ligand LX, such as in particular a ligand derived from acetylacetone, from a .beta.-ketoester, from a malonic ester or from an allyl compound, [0040] are highly suitable. [0041] According to an even more preferred form, the catalyst corresponds to the formula (IV) where the symbol R.sup.5 of the catalyst represents Hal and y=2. [0042] The ligands R.sup.4 of the preferred catalyst (IV) can be identical to or different from the UHCs (v) of the auxiliary. [0043] The iridium-based catalyst can be supported, as is disclosed, for example, in U.S. Pat. No. 6,177,585 and GB-A-1 526 324. [0044] The catalytic system used in accordance with the process according to the invention makes it possible to reduce the amount of catalyst necessary for the achievement of a full degree of conversion DC of the silane of formula (II): (Hal-(R.sup.2R.sup.3)Si--H) and/or to increase the selectivity S for a given and fixed DC. [0045] This catalytic system is advantageously composed: [0046] of an organometallic catalyst based on iridium in the oxidation state I or III, [0047] of one or more auxiliaries each introduced in a minimum amount of 20 mol % with respect to the metal. [0048] This or these auxiliaries can be used in the liquid or solid form. Provided that they are liquid, they can be introduced in an amount such that, in the reaction medium, they, in addition to acting as hydrosilylation promoter, act as solvent for the reaction. [0049] The fact of being able to be employed in liquid form is a very major operational advantage for the process of the invention. [0050] The possible function of solvent of the auxiliary can also make it possible, in particular when it is a heavy solvent (namely, a solvent having a boiling point at atmospheric pressure which is greater than that of the compound of formula (I), such as, for example, a polyether), to improve the stability of the reaction medium and thus the safety of the process. In addition, this offers possibilities of easy recovery of the catalyst and thus of recycling the latter. Continue reading... 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